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Статті в журналах з теми "Driven diffusive model"
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LI, YAN, LINYAN ZHANG, DAGEN LI, and HONG-BO SHI. "SPATIOTEMPORAL DYNAMICS OF A DIFFUSIVE LESLIE-TYPE PREDATOR–PREY MODEL WITH BEDDINGTON–DEANGELIS FUNCTIONAL RESPONSE." Journal of Biological Systems 28, no. 03 (August 28, 2020): 785–809. http://dx.doi.org/10.1142/s0218339020500175.
Повний текст джерелаАнотація:
In this paper, we study the spatiotemporal dynamics of a diffusive Leslie-type predator–prey system with Beddington–DeAngelis functional response under homogeneous Neumann boundary conditions. Preliminary analysis on the local asymptotic stability and Hopf bifurcation of the spatially homogeneous model based on ordinary differential equations is presented. For the diffusive model, firstly, it is shown that Turing (diffusion-driven) instability occurs which induces spatial inhomogeneous patterns. Next, it is proved that the diffusive model exhibits Hopf bifurcation which produces temporal inhomogeneous patterns. Furthermore, at the points where the Turing instability curve and Hopf bifurcation curve intersect, it is demonstrated that the diffusive model undergoes Turing–Hopf bifurcation and exhibits spatiotemporal patterns. Numerical simulations are also presented to verify the theoretical results.
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O’Loan, O. J., M. R. Evans, and M. E. Cates. "Shear-induced clustering in a simple driven diffusive model." Physica A: Statistical Mechanics and its Applications 258, no. 1-2 (September 1998): 109–22. http://dx.doi.org/10.1016/s0378-4371(98)00225-8.
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Botto, D., A. Pelizzola, and M. Pretti. "Dynamical transitions in a driven diffusive model with interactions." EPL (Europhysics Letters) 124, no. 5 (December 27, 2018): 50004. http://dx.doi.org/10.1209/0295-5075/124/50004.
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Pawlik, Grzegorz, Tomasz Wysoczanski, and Antoni Mitus. "Complex Dynamics of Photoinduced Mass Transport and Surface Relief Gratings Formation." Nanomaterials 9, no. 3 (March 4, 2019): 352. http://dx.doi.org/10.3390/nano9030352.
Повний текст джерелаАнотація:
The microscopic and semi-macroscopic mechanisms responsible for photoinduced mass transport in functionalized azo-polymers are far from deeply understood. To get some insight into those mechanisms on “microscopic” scale, we studied the directed photoinduced motion of single functionalized polymer chains under various types of polarized light illumination using Monte Carlo bond fluctuation model and our kinetic Monte Carlo model for photoinduced mass transport. We found sub-diffusive, diffusive and super-diffusive regimes of the dynamics of single chains at constant illumination and mostly super-diffusive regime for directed motion in the presence of the gradient of light intensity. This regime is more enhanced for long than for short chains and it approaches the ballistic limit for very long chains. We propose a physical picture of light-driven inscription of Surface Relief Gratings (SRG) as corresponding to a dynamical coexistence of normal and anomalous diffusion in various parts of the system. A simple continuous time random walk model of SRG inscription based on this physical picture reproduced the light-driven mass transport found in experiments as well as the fine structure of SRG.
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Souna, Fethi, Salih Djilali, and Fayssal Charif. "Mathematical analysis of a diffusive predator-prey model with herd behavior and prey escaping." Mathematical Modelling of Natural Phenomena 15 (2020): 23. http://dx.doi.org/10.1051/mmnp/2019044.
Повний текст джерелаАнотація:
In this paper, we consider a new approach of prey escaping from herd in a predator-prey model with the presence of spatial diffusion. First, the sensitivity of the equilibrium state density with respect to the escaping rate has been studied. Then, the analysis of the non diffusive system was investigated where boundedness, local, global stability, Hopf bifurcation are obtained. Besides, for the diffusive system, we proved the occurrence of Hopf bifurcation and the non existence of diffusion driven instability. Furthermore, the direction of Hopf bifurcation has been proved using the normal form on the center manifold. Some numerical simulations have been used to illustrate the obtained results.
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Eroglu, Fatma G., Songul Kaya, and Leo G. Rebholz. "POD-ROM for the Darcy–Brinkman equations with double-diffusive convection." Journal of Numerical Mathematics 27, no. 3 (September 25, 2019): 123–39. http://dx.doi.org/10.1515/jnma-2017-0122.
Повний текст джерелаАнотація:
Abstract This paper extends proper orthogonal decomposition reduced order modeling to flows governed by double diffusive convection, which models flow driven by two potentials with different rates of diffusion. We propose a reduced model based on proper orthogonal decomposition, present a stability and convergence analyses for it, and give results for numerical tests on a benchmark problem which show it is an effective approach to model reduction in this setting.
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Elwakil, Sayed A., Mohsen A. Zahran, Refaat Sabry, and Emad K. El-Shewy. "New Travelling Wave Solutions for an Asymmetric Model of a Rod in a Lattice Fluid with Nonlinear Advection." Zeitschrift für Naturforschung A 61, no. 9 (September 1, 2006): 430–38. http://dx.doi.org/10.1515/zna-2006-0902.
Повний текст джерелаАнотація:
Based on the modified extended tanh-function method, we consider the continuum problem of the driven diffusive flow of particles behind an impenetrable obstacle (rod) of the length L. The results show that the presence of an obstacle, whether stationary or moving, in a driven diffusive flow with nonlinear drift will distort the local concentration profile to a state which divided the (x,y)-plane into two regions. The concentration is relatively higher in one side than the other side, apart from the value of , where D is the diffusion coefficient and v is the drift velocity. This problem has relevance for the size segregation of particulate matter which results from the relative motion of different-size paricles induced by shaking. The obtained soultions include soliton, periodical, rational and singular solutions.
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Christensen, Ulrich R., Julien Aubert, and Peter Olson. "Convection-driven planetary dynamos." Proceedings of the International Astronomical Union 2, S239 (August 2006): 188–95. http://dx.doi.org/10.1017/s1743921307000403.
Повний текст джерелаАнотація:
AbstractNumerical simulations of convection-driven dynamos in rotating spherical shells are employed to better understand the observed strength and geometry of planetary magnetic fields. The model computations cannot be performed for realistic values of several of the control parameters. By varying parameters within the accessible range, it is possible to derive scaling laws for the magnetic field strength and the flow velocity in the dynamo region and for the dipole moment. Our scaling laws suggest that, even though diffusivities are far too large in the models, diffusive processes do not play an important role, just as in planetary cores. Extrapolating the scaling laws to planetary values of the control parameters leads to reasonable predictions for the field strength in the dynamo region and fits the observed dipole moments decently, in particular in the cases of Earth and Jupiter. For Mercury, which does not fit well when applying the scaling laws in a straightforward way, a model is proposed in which the upper part of the fluid core is stably stratified and the dynamo operates only in its deep regions. The time-varying dynamo field must diffuse through the stable region and is attenuated by the skin effect. The model explains why Mercury has a very weak but probably dipole-dominated magnetic field.
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Zhou, Jun. "Bifurcation Analysis of a Diffusive Predator–Prey Model with Bazykin Functional Response." International Journal of Bifurcation and Chaos 29, no. 10 (September 2019): 1950136. http://dx.doi.org/10.1142/s0218127419501360.
Повний текст джерелаАнотація:
This paper deals with a diffusive predator–prey model with Bazykin functional response. The parameter regions for the stability and instability of the unique constant steady state are derived. The Turing (diffusion-driven) instability which induces spatial inhomogeneous patterns, the existence of time-periodic orbits which produce temporal inhomogeneous patterns, the existence and nonexistence of nonconstant steady state positive solutions are proved. Numerical simulations are presented to verify and illustrate the theoretical results.
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Cao, Pei-Chao, Yu-Gui Peng, Ying Li, and Xue-Feng Zhu. "Phase-Locking Diffusive Skin Effect." Chinese Physics Letters 39, no. 5 (April 1, 2022): 057801. http://dx.doi.org/10.1088/0256-307x/39/5/057801.
Повний текст джерелаАнотація:
We explore the exceptional point (EP) induced phase transition and amplitude/phase modulation in thermal diffusion systems. We start from the asymmetric coupling double-channel model, where the temperature field is unbalanced in the amplitude and locked in the symmetric phase. By extending into the one-dimensional tight-binding non-Hermitian lattice, we study the convection-driven phase locking and the asymmetric-couplinginduced diffusive skin effect with the high-order EPs in static systems. Combining convection and asymmetric couplings, we further show the phase-locking diffusive skin effect. Our work reveals the mechanism of controlling both the amplitude and phase of temperature fields in thermal coupling systems and has potential applications in non-Hermitian topology in thermal diffusion.
Дисертації з теми "Driven diffusive model"
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O'Loan, Owen James. "Phase transitions and ordering in model driven diffusive systems." Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/12718.
Повний текст джерелаАнотація:
In contrast to the equilibrium case, there is no general theoretical framework for the treatment of many-body nonequilibrium systems. Therefore, simple model systems, amenable to detailed analytical or numerical treatment, are important in the understanding of such systems. Phase transitions and ordering are fundamental phenomena which have been extensively studied in equilibrium statistical physics. In this work, we investigate these phenomena in several model driven diffusive systems. We introduce the 'bus route model', a simple microscopic model in which jamming of a conserved driven species is mediated by the presence of a non-conserved quantity. Jamming proceeds via a strict phase transition only in a prescribed limit; outside this limit, we find sharp crossovers and transient coarsening. Next, we study flocking, the collective motion of many self-driven entities, in a one-dimensional lattice model. We find the existence of an ordered phase characterized by the presence of a single large 'flock' which exhibits stochastic reversals in direction. Using numerical finite-size scaling, we analyse the continuous phase transition from this ordered phase to a homogeneous phase and we calculate critical exponents. Finally, we study a model of shear-induced clustering; we find evidence for a discontinuous jamming transition with hysteresis. We also study the kinetics of jamming.
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Mukherjee, Sayak. "Applications of Field Theory to Reaction Diffusion Models and Driven Diffusive Systems." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/39293.
Повний текст джерелаАнотація:
In this thesis, we focus on the steady state properties of two systems which are genuinely out of equilibrium. The first project is an application of dynamic field theory to a specific non equilibrium critical phenomenon, while the second project involves both simulations and analytical calculations. The methods of field theory are used on both these projects. In the first part of this thesis, we investigate a generalization of the well-known field theory for directed percolation (DP). The DP theory is known to describe an evolving population, near extinction. We have coupled this evolving population to an environment with its own nontrivial spatio-temporal dynamics. Here, we consider the special case where the environment follows a simple relaxational (model A) dynamics. We find two marginal couplings with upper critical dimension of four, which couple the two theories in a nontrivial way. While the Wilson-Fisher fixed point remains completely unaffected, a mismatch of time scales destabilizes the usual DP fixed point. Some open questions and future work remain.
In the second project, we focus on a simple particle transport model far from equilibrium, namely, the totally asymmetric simple exclusion process (TASEP). While its stationary properties are well studied, many of its dynamic features remain unexplored. Here, we focus on the power spectrum of the total particle occupancy in the system. This quantity exhibits unexpected oscillations in the low density phase. Using standard Monte Carlo simulations and analytic calculations, we probe the dependence of these oscillations on boundary effects, the system size, and the overall particle density. Our simulations are fitted to the predictions of a linearized theory for the fluctuation of the particle density. Two of the fit parameters, namely the diffusion constant and the noise strength, deviate from their naive bare values [6]. In particular, the former increases significantly with the system size. Since this behavior can only be caused by nonlinear effects, we calculate the lowest order corrections in perturbation theory. Several open questions and future work are discussed.Ph. D.
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Pesheva, Nina Christova. "A mean-field method for driven diffusive systems based on maximum entropy principle." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54398.
Повний текст джерелаАнотація:
Here, we propose a method for generating a hierarchy of mean-field approximations to study the properties of the driven diffusive Ising model at nonequilibrium steady state. In addition, the present study offers a demonstration of the practical application of the information theoretic methods to a simple interacting nonequilibrium system. The application of maximum entropy principle to the system, which is in contact with a heat reservoir, leads to a minimization principle for the generalized Helmholtz free energy. At every level of approximation the latter is expressed in terms of the corresponding mean—field variables. These play the role of variational parameters. The rate equations for the mean-field variables, which incorporate the dynamics of the system, serve as constraints to the minimization procedure.
The method is applicable to high temperatures as well to the low temperature phase coexistence regime and also has the potential for dealing with first-order phase transitions. At low temperatures the free energy is nonconvex and we use a Maxwell construction to find the relevant information for the system.
To test the method we carry out numerical calculations at the pair level of approximation for the 2-dimensional driven diffusive Ising model on a square lattice with attractive interactions. The results reproduce quite well all the basic properties of the system as reported from Monte Carlo simulations.Ph. D.
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Waseem, Abdullah. "Numerical Homogenization and Model Reduction for Transient Heat, Diffusion and coupled Mechanics Problems." Thesis, Ecole centrale de Nantes, 2020. http://www.theses.fr/2020ECDN0028.
Повний текст джерелаАнотація:
Dans cette thèse, des techniques d'homogénéisation numérique efficaces en termes de calcul sont présentées pour les phénomènes de diffusion dans des matériaux hétérogènes. Comme étape préliminaire, une réduction de modèle pour l'équation de diffusion de chaleur transitoire est effectuée à la microéchelle en utilisant la synthèse en mode composants, qui fournit une description émergente enrichie-continuum à l’échelle macroscopique. Sur la base de la localisation des variables d'enrichissement, soit sur les nœuds d'éléments finis, soit sur les points de quadrature, deux schémas de discrétisation spatiale sont analysés pour le diplacement milieu continu. La formulation du potentiel chimique et des champs de déformation est utilisée, ce qui permet l'utilisation d'éléments finis continus en C0 standard. Le problème de la micro-échelle, qui implique généralement une solution coûteuse du problème de la mécanique de diffusion de masse couplée est maintenant remplacée par un ensemble d'équations différentielles ordinaires grâce à la réduction du modèle. Enfin, une approche alternative de réduction de modèle utilisant la mécanique basée sur les données est explorée. Il repose sur une recherche directe et une interpolation à partir d'une base de données au lieu de la solution d'un problème microscopique. La base de données est construite et stockée en utilisant les calculs microscopiques dans une étape hors ligne. Il fournit également une voie pour étendre la méthode de réduction du modèle proposée au régime non linéaireIn this thesis computationally efficient numerical homogenization techniques are presented for diffusion phenomena in heterogeneous materials. As a preliminary step, a model reduction for the transient heat diffusion equation is performed at the micro-scale using component mode synthesis, which provides an emergent enriched-continuum description at the macro-scale. Based on the location of the enrichmentvariables, either on the finite element nodes or the quadrature points, two spatial discretization schemes are analyzed for the enrichedcontinuum. The proposed model reduction is also extended to the transient mass diffusion coupled to the mechanics with application to lithium-ion batteries. Chemical potential and strain fields formulation is used which allows the use of standard C0-continuous finite elements. The micro-scale problem, which usually involves an expensive solution of the coupled mass diffusionmechanics problem is now replaced by a set of ordinary differential equations through model reduction. Finally, an alternative model reduction approach using data-driven mechanics is explored. It relies on a direct search and interpolation from a database instead of the solution of a microscopic problem. The database is constructed and stored using the microscopic calculations in an offline stage. It also provides a route to extend the proposed model reduction method to the nonlinear regime
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Köthe, Alexandra [Verfasser], and Anna [Akademischer Betreuer] Marciniak-Czochra. "Hysteresis-driven pattern formation in Reaction-diffusion-Ode models / Alexandra Köthe ; Betreuer: Anna Marciniak-Czochra." Heidelberg : Universitätsbibliothek Heidelberg, 2013. http://d-nb.info/1177809214/34.
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Marinelli, Alessio. "Fractional diffusion: biological models and nonlinear problems driven by the s-power of the Laplacian." Doctoral thesis, Università degli studi di Trento, 2016. https://hdl.handle.net/11572/368483.
Повний текст джерелаАнотація:
In the classical theory, the fractional diffusion is ruled by two different types of fractional Laplacians. Formerly known since 60s, the spectral fractional Laplacian had an important development in the recent mathematical study with the initial contributes of L. Caffarelli, L. Silvestre and X. Cabré, X.Tan. The integral version of the fractional Laplacian, recently discussed by M. Fukushima, Y. Oshima, M Takeda, and Song, Vondracek, is considered in a
semilinear elliptic problem in presence of a general logistic function and an indefinite weight.
In particular we look for a multiplicity result for the associated Dirichlet problem. In the second part, starting from the classical works of T.Hillen and G. Othmer and taking the Generalized velocity jump processes presented in a recent work of J.T.King, we obtain the fractional diffusion as limit of this last processes using the technique used in another recent work of Mellet, without the classical Hilbert or Cattaneo approximation's methods.
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Pagliarani, Stefano. "Portfolio optimization and option pricing under defaultable Lévy driven models." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423519.
Повний текст джерелаАнотація:
In this thesis we study some portfolio optimization and option pricing problems in market models where the dynamics of one or more risky assets are driven by Lévy processes, and it is divided in four independent parts.
In the first part we study the portfolio optimization problem, for the logarithmic terminal utility and the logarithmic consumption utility, in a multi-defaultable Lévy driven model.
In the second part we introduce a novel technique to price European defaultable claims when the pre-defaultable dynamics of the underlying asset follows an exponential Lévy process.
In the third part we develop a novel methodology to obtain analytical expansions for the prices of European derivatives, under stochastic and/or local volatility models driven by Lévy processes, by analytically expanding the integro-differential operator associated to the pricing problem.
In the fourth part we present an extension of the latter technique which allows for obtaining analytical expansion in option pricing when dealing with path-dependent Asian-style derivatives.In questa tesi studiamo alcuni problemi di portfolio optimization e di option pricing in modelli di mercato dove le dinamiche di uno o più titoli rischiosi sono guidate da processi di Lévy. La tesi é divisa in quattro parti indipendenti. Nella prima parte studiamo il problema di ottimizzare un portafoglio, inteso come massimizzazione di un’utilità logaritmica della ricchezza finale e di un’utilità logaritmica del consumo, in un modello guidato da processi di Lévy e in presenza di fallimenti simultanei. Nella seconda parte introduciamo una nuova tecnica per il prezzaggio di opzioni europee soggette a fallimento, i cui titoli sottostanti seguono dinamiche che prima del fallimento sono rappresentate da processi di Lévy esponenziali. Nella terza parte sviluppiamo un nuovo metodo per ottenere espansioni analitiche per i prezzi di derivati europei, sotto modelli a volatilità stocastica e locale guidati da processi di Lévy, espandendo analiticamente l’operatore integro-differenziale associato al problema di prezzaggio. Nella quarta, e ultima parte, presentiamo un estensione della tecnica precedente che consente di ottenere espansioni analitiche per i prezzi di opzioni asiatiche, ovvero particolari tipi di opzioni il cui payoff dipende da tutta la traiettoria del titolo sottostante.
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Sena, Elisa Thomé. "Um modelo de exclusão assimétrico para o transporte de partículas mediado por motores moleculares." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-20052008-120606/.
Повний текст джерелаАнотація:
Motores moleculares são proteínas capazes de transportar objetos tais como vesículas, organelas e macromoléculas ao longo do citoesqueleto. Tratam-se de dispositivos bastante interessantes do ponto de vista físico, pois produzem trabalho em um ambiente extremamente ruidoso. Recentemente, diversos experimentos realizados in vivo têm revelado que objetos transportados por motores moleculares ao longo dos microtúbulos apresentam movimento bidirecional. Embora o movimento unidirecional dos motores envolvidos no transporte destes objetos seja bem caracterizado tanto experimentalmente quanto teoricamente, o movimento bidirecional das partículas transportadas pelos motores ainda não é bem entendido. Contudo, acredita-se que este fenômeno seja causado pela cooperatividade dos motores moleculares. Existem na literatura diversos trabalhos que visam descrever o comportamento coletivo de partículas locomovendo-se sobre uma rede unidimensional com interações de volume excluído e taxas de transição assimétricas. Estes modelos são conhecidos como TASEP (Totally asymmetric simple exclusion processes ) ou ASEP (Asymmetric simple exclusion processes ) e fazem parte de uma classe de modelos denominados sistemas difusivos dirigidos_. Embora alguns autores tenham utilizado modelos do tipo ASEP e TASEP para descrever o movimento dos motores moleculares exclusivamente [37], [38], não há ainda nesta visão microscópica, extensões deste modelo para incorporar as partículas cuja dinâmica depende exclusivamente da presença de motores. No presente trabalho propomos um modelo de exclusão, desenvolvido com o intuito de descrever o movimento conjunto de motores moleculares e das partículas carregadas pelos mesmos, as quais por simplicidade denominamos vesículas. Neste modelo, as vesículas não possuem dinâmica própria, ou seja, dependem da interação com os motores moleculares para se movimentarem. Procuramos soluções analíticas para este modelo para o 1 RESUMO 2 caso em que há apenas uma vesícula locomovendo-se sobre a rede. Utilizando o método das matrizes [32], calculamos a velocidade média da vesícula no estado estacionário e analisamos seu comportamento em situações de interesse.Molecular motors are proteins that transport objects such as vesicles, organelles and macromolecules along the cytoskeletum of cells. For physics, they are very interesting devices because they are able to generate work in an extremely viscous environment. Recently, many in vivo experiments have revealed that objects transported by molecular motors move bidirectionally along microtubules. Although the unidirectional movement of such molecular motors is experimentally and theoretically well characterized, the movement of particles transported by these motors is not well understood yet. However, this fenomenum is believed to be caused by the cooperativity of molecular motors. A great number of works are found in literature, which were formulated to describe the collective behaviour of many particles moving in a one-dimensional lattice with a preferred hop rate and exclusion. These models are known as TASEP (Totally asymmetric simple exclusion processes) or ASEP (Asymmetric simple exclusion processes) and are part of a class of models named _driven di_usive systems_. Although some authors made use of ASEP and TASEP models to describe the movement of molecular motors [37], [38], there is not yet, in this microscopic point of view, extensions of these models capable of incorporate particles which the dynamics depends exclusivaly from the presence of motors. In this work we propose a exclusion model developed to describe the joint movement of molecular motors and particles, generally called vesicles. In this model, vesicles do not have a proper dynamics, that is, they on the interaction with molecular motors to move. We look after analytical solutions of this model when there is only one vesicle moving on the lattice. We use a matrix formulation [32] to obtain the mean velocity of the vesicle and analyse its behaviour in situations of interest.
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Engelbrecht, Adrian [Verfasser], Peter [Akademischer Betreuer] Buxmann, and Alexander [Akademischer Betreuer] Kock. "Discovery and Diffusion of Digital Innovations – An Analysis of Enterprise Social Networks and Data-Driven Business Models / Adrian Engelbrecht ; Peter Buxmann, Alexander Kock." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1177241692/34.
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Herrenkind, Bernd, Alfred Benedikt Brendel, Ilja Nastjuk, Maike Greve, and Lutz M. Kolbe. "Investigating end-user acceptance of autonomous electric buses to accelerate diffusion." Elsevier, 2019. https://publish.fid-move.qucosa.de/id/qucosa%3A75922.
Повний текст джерелаАнотація:
To achieve the widespread diffusion of autonomous electric buses (AEBs) and thus harness their environmental potential, a broad acceptance of new technology-based mobility concepts must be fostered. Still, there remains little known about the factors determining their acceptance, especially in the combination of vehicles with alternative fuels and autonomous driving modes, as is the case with AEBs. In this study, we first conducted qualitative research to identify relevant factors influencing individual acceptance of autonomously driven electric buses. We then developed a comprehensive research model that was validated through a survey of 268 passengers of an AEB, operated in regular road traffic in Germany. The results indicate that a mix of individual factors, social impacts, and system characteristics determine an individual’s acceptance of AEBs. Notably, it is important that users perceive AEBs, not only as advantageous, but also trustworthy, enjoyable, and in a positive social light. Our research supplements the existing corpora by demonstrating the importance of individual acceptance and incorporating it to derive policy implications.
Книги з теми "Driven diffusive model"
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Cockburn, Iain. The diffusion of science driven drug discovery: Organizational change in pharmaceutical research. Cambridge, MA: National Bureau of Economic Research, 1999.
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Ansermet, J. Ph. Spintronics with metallic nanowires. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533060.013.3.
Повний текст джерелаАнотація:
This article focuses on spintronics with metallic nanowires. It begins with a review of the highlights of spintronics research, paying attention to the very important developments accomplished with tunnel junctions. It then considers the effect of current on magnetization before discussing spin diffusion and especially spin-dependent conductivities, spin-diffusion lengths, and spin accumulation. It also examines models for spin-polarized currents acting on magnetization, current-induced magnetization switching, and current-driven magnetic excitations. It concludes with an overview of resonant-current excitations, with emphasis on spin-valves and tunnel junctions as well as resonant excitation of spin-waves, domain walls and vortices. In addition, the article reflects on the future of spintronics, citing in particular the potential of the spin Hall effect as the method of generating spin accumulation, free of charge accumulation.
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Kuo, Raymond C. Following the Leader. Stanford University Press, 2021. http://dx.doi.org/10.11126/stanford/9781503628434.001.0001.
Повний текст джерелаАнотація:
Nations have powerful reasons to get their military alliances right. When security pacts go well, they underpin regional and global order; when they fail, they spread wars across continents as states are dragged into conflict. We would, therefore, expect states to carefully tailor their military partnerships to specific conditions. This expectation, Raymond C. Kuo argues, is wrong. Following the Leader argues that most countries ignore their individual security interests in military pacts, instead converging on a single, dominant alliance strategy. The book introduces a new social theory of strategic diffusion and emulation, using case studies and advanced statistical analysis of alliances from 1815 to 2003. In the wake of each major war that shatters the international system, a new hegemon creates a core military partnership to target its greatest enemy. Secondary and peripheral countries rush to emulate this alliance, illustrating their credibility and prestige by mimicking the dominant form. Be it the NATO model that seems so commonsense today, or the realpolitik that reigned in Europe of the late nineteenth century, a lone alliance strategy has defined broad swaths of diplomatic history. It is not states' own security interests driving this phenomenon, Kuo shows, but their jockeying for status in a world periodically remade by great powers.
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Nissenson, Allen R., John Moran, and Robert Provenzano. Overview of dialysis patient management and future directions. Edited by Jonathan Himmelfarb. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199592548.003.0267_update_001.
Повний текст джерелаАнотація:
Nearly 2 million patients worldwide have end-stage renal disease (ESRD) and require dialysis or kidney transplantation. The advent of clinical dialysis in the 1950s has had a huge impact on the way ESRD and acute kidney injury are managed, but several decades later, the morbidity and mortality in patients with ESRD remain unacceptably high and patients often have a poor quality of life. Many believe that we have focused attention on a few key treatment-related outcomes, and have done well with these (i.e. anaemia, adequacy of dialysis, metabolic bone disease), but achieving great results in only these domains has clearly not been sufficient to drive improvements in survival or patient-reported outcomes. Recent experience with integrated care management, focusing on comorbidity management, offers promise. In addition, a number of investigators have been challenging the current thrice-weekly, diffusion-based treatment paradigm and have been developing approaches to emulate the function of natural kidneys. Thus an ideal care delivery model would focus on the holistic needs of the patient with kidney disease, while the ideal form of renal replacement therapy would mimic native kidneys, operating continuously, removing solutes with a molecular-weight spectrum similar to that of native kidneys, removing water and solutes on the basis of individual patient needs, and would be biocompatible, wearable, and ideally implantable. It would also be low cost, reliable, and safe. A few years ago, these technical requirements would have seemed impossible to achieve, but with advances in the sciences of nanotechnology and microfluidics, renal replacement of the future may come closer to this ideal.
Частини книг з теми "Driven diffusive model"
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Föll, Fabian, Valerie Gerber, Claus-Dieter Munz, Berhand Weigand, and Grazia Lamanna. "On the Consideration of Diffusive Fluxes Within High-Pressure Injections." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 195–208. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_12.
Повний текст джерелаАнотація:
Abstract Mixing characteristics of supercritical injection studies were analyzed with regard to the necessity to include diffusive fluxes. Therefore, speed of sound data from mixing jets were investigated using an adiabatic mixing model and compared to an analytic solution. In this work, we show that the generalized application of the adiabatic mixing model may become inappropriate for subsonic submerged jets at high-pressure conditions. Two cases are discussed where thermal and concentration driven fluxes are seen to have significant influence. To which extent the adiabatic mixing model is valid depends on the relative importance of local diffusive fluxes, namely Fourier, Fick and Dufour diffusion. This is inter alia influenced by different time and length scales. The experimental data from a high-pressure n-hexane/nitrogen jet injection were investigated numerically. Finally, based on recent numerical findings, the plausibility of different thermodynamic mixing models for binary mixtures under high pressure conditions is analyzed.
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Figueroa-López, José E. "Jump-Diffusion Models Driven by Lévy Processes." In Handbook of Computational Finance, 61–88. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-17254-0_4.
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De Smet, Patrick, Rui Luís Vieira Pires Marques Pires, and Danny De Vleeschauwer. "Activity Driven Non-linear Diffusion for Colour Image Segmentation." In Noblesse Workshop on Non-Linear Model Based Image Analysis, 183–87. London: Springer London, 1998. http://dx.doi.org/10.1007/978-1-4471-1597-7_29.
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Schilling, Kurt G., Baxter Rogers, Adam W. Anderson, and Bennett A. Landman. "Current Challenges and Future Directions in Diffusion MRI: From Model- to Data- Driven Analysis." In Computational Diffusion MRI, 63–78. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-52893-5_6.
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Ke, Yuanyuan, Jing Li, and Yifu Wang. "Density-Suppressed Motility System." In Financial Mathematics and Fintech, 275–339. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-3763-7_5.
Повний текст джерелаАнотація:
AbstractThe reaction–diffusion models can reproduce a wide variety of exquisite spatio-temporal patterns arising in embryogenesis, development and population dynamics due to the diffusion-driven (Turing) instability [102, 162].
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Załuska-Kotur, M. A., Stanisław Krukowski, and Łukasz A. Turski. "Driven Diffusion in a Model of the O/W(110) System." In Collective Diffusion on Surfaces: Correlation Effects and Adatom Interactions, 59–69. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0816-7_6.
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Periquito, João S., Martin Meier, Thoralf Niendorf, Andreas Pohlmann, and Neil Peter Jerome. "Renal MRI Diffusion: Experimental Protocol." In Methods in Molecular Biology, 419–28. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-0978-1_24.
Повний текст джерелаАнотація:
AbstractRenal diffusion-weighted imaging (DWI) can be used to obtain information on the microstructure of kidney tissue, and has the potential to provide MR-biomarkers for functional renal imaging. Here we describe in a step-by-step experimental protocol the MRI method for measuring renal diffusion coefficients in rodents using ADC or IVIM models. Both methods provide quantification of renal diffusion coefficients; however, IVIM, a more complex model, allows for the calculation of the pseudodiffusion and fraction introduced by tissue vascular and tubular components. DWI provides information of renal microstructure contributing to the understanding of the physiology and the underlying processes that precede the beginning of pathologies.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This experimental protocol chapter is complemented by two separate chapters describing the basic concept and data analysis.
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Jerome, Neil Peter, and João S. Periquito. "Analysis of Renal Diffusion-Weighted Imaging (DWI) Using Apparent Diffusion Coefficient (ADC) and Intravoxel Incoherent Motion (IVIM) Models." In Methods in Molecular Biology, 611–35. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-0978-1_37.
Повний текст джерелаАнотація:
AbstractAnalysis of renal diffusion-weighted imaging (DWI) data to derive markers of tissue properties requires careful consideration of the type, extent, and limitations of the acquired data. Alongside data quality and general suitability for quantitative analysis, choice of diffusion model, fitting algorithm, and processing steps can have consequences for the precision, accuracy, and reliability of derived diffusion parameters. Here we introduce and discuss important steps for diffusion-weighted image processing, and in particular give example analysis protocols and pseudo-code for analysis using the apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) models. Following an overview of general principles, we provide details of optional steps, and steps for validation of results. Illustrative examples are provided, together with extensive notes discussing wider context of individual steps, and notes on potential pitfalls.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This analysis protocol chapter is complemented by two separate chapters describing the basic concepts and experimental procedure.
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Li, Bingfang, and Gaihui Guo. "Diffusion-Driven Instability and Hopf Bifurcation in Spatial Homogeneous Brusselator Model." In Advances in Intelligent and Soft Computing, 249–55. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29390-0_41.
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Proesmans, M., E. J. Pauwels, L. J. Van Gool, T. Moons, and A. Oosterlinck. "Geometry-Driven Diffusion: Coupled Diffusion Maps as a Model for Excitatory and Inhibitory Behaviour in Vision." In ICANN ’93, 224–29. London: Springer London, 1993. http://dx.doi.org/10.1007/978-1-4471-2063-6_52.
Повний текст джерелаТези доповідей конференцій з теми "Driven diffusive model"
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de Lemos, Marcelo J. S. "Modelling of Double Diffusion in Turbulent Mass Transport in Porous Media." In ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56764.
Повний текст джерелаАнотація:
This work presents derivations of macroscopic heat and mass transport equations for turbulent flow in permeable structures. Two driving mechanisms are considered to contribute to the overall momentum transport, namely temperature driven and concentration driven mass fluxes. Double-diffusive natural convection mechanism is investigated for the fluid phase in turbulent regime. Equations are presented based on two distinct procedures. The first method considers time averaging of the local instantaneous mass transport equation before the volume average operator is applied. The second methodology employs both averaging operators but in a reverse order. This work is intended to demonstrate that additional transport mechanisms are mathematically derived if temperature, concentration and velocity present simultaneously time fluctuations and spatial deviations within the domain of analysis. A modeled form for the final mass transport equation is presented where turbulent transfer is based on a macroscopic version of the k-ε model.
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Terala, Shashank, Sandip Mazumder, Gurpreet Matharu, Dhaval Vaishnav, and Syed Ali. "A Reduced Three-Phase Model for Solidification of Liquid in Large Tanks." In ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-95217.
Повний текст джерелаАнотація:
Abstract A liquid water-urea mixture is stored onboard diesel vehicles and used for exhaust aftertreatment. In cold weather conditions, the mixture may freeze and the freezing process may span over a day. In the first part of our study (Journal of Thermal Science and Engineering Applications — Transactions of the ASME, Vol. 13, p. 011008, 2021) it was shown that traditional computational methods are impractical for modeling such large-duration freezing processes because of restrictions in the time-step size posed by numerical stability and physical time-scale considerations. A model, in which natural convection driven thermal transport is treated as a diffusive process, was developed and demonstrated. Since the flow field was not computed in this model, the computations were found to be orders of magnitude more efficient than traditional methods. This preliminary model did not account for the expansion of ice. Here, a new model that accounts for the expansion of ice and the consequent rise of the initial air-water/ice interface (ice dome formation) is presented. An additional conservation equation for excess volume fraction is introduced to this end and is solved using the unstructured finite-volume procedure and sub-time-stepping. Since the flow field is not computed, the air-water/ice interface is tracked using a new algorithm similar to the traditional volume-of-fluid method, but one that constructs fluxes using a diffusive formulation rather than an advective one. Validation studies in full-scale three-dimensional tanks show good agreement with measured temperature-time data. It is found that the air-water/ice interface first evolves to a concave shape before finally becoming a convex ice dome after full solidification.
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Guo, Zhenyu, Wenyue Sun, and Sathish Sankaran. "Efficient Reservoir Management with a Reservoir Graph Network Model." In SPE Western Regional Meeting. SPE, 2022. http://dx.doi.org/10.2118/209337-ms.
Повний текст джерелаАнотація:
Abstract Efficient reservoir models are more desirable for fast-paced reservoir management. Moreover, due to the complexity of flow underground, it is also essential to capture the most fundamental physics for model reliability. Though running fast, pure data-driven models often suffer from the issues associated with interpretability, physical consistency, and ability to forecast. On the other hand, we have used full-physics simulation models to mimic and investigate hydrocarbon systems for over several decades. However, considering its infrequent model updates related to high model complexity, it is a big challenge to manage reservoirs using full-physics models in short cycles. The objective here is to propose an approach that blends reservoir physics with data-driven models to fit in the framework of dynamic reservoir management. We propose to use a reservoir graph network (RGNet) modeling approach based on diffusive time-offlight (DTOF) concept to simulate reservoir behaviors. By assimilating field observation data (such as pressure and rates), an RGNet model can be used for future predictions, scenario studies and well-control optimizations. By discretizing DTOF of a three-dimensional system with multiple wells, RGNet simplifies the system into a graph network represented by a set of one-dimensional grid blocks that significantly reduces the system complexity and run time. RGNet can also handle multiple flow problems with various types of physics. In this work, we investigate multiple grid connectivity methods to develop reliable and parsimonious models for large scale systems. In addition, we propose a more robust method to assimilate static pressure data, when available. We applied the proposed approach to a synthetic example. Two different history matching algorithms, the ensemble smoother with multiple data assimilation (ES-MDA) and an adjoint-based method, are compared. While ES-MDA provides the capability for uncertainty analysis, an adjoint-based method generally requires fewer simulation runs to generate a posterior model. With the proposed gridding methods, RGNet model calibration can be achieved without system redundancy and spurious longdistance well-connectivity. Also, by using a more stable pressure matching technique, we show that pressure data are better matched and reservoir volume is accurately characterized. RGNet provides a novel hybrid physics and data-driven reservoir modeling method to fit in closed-loop reservoir management. As RGNet models are combined with fundamental flowing physics, the calibrated model parameters are easy to interpret and understand. An RGNet model runs with far less computational cost than required by a full-physics model, which allows it to be a more practical solution to history match, predict and optimize real assets.
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Ren, Qinlong, and Cho Lik Chan. "Transient Double-Diffusive Convection in a Vertical Cavity With Soret and Dufour Effects by Lattice Boltzmann Method on CUDA Platform." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52359.
Повний текст джерелаАнотація:
Double diffusive flow in a cavity has attracted lots of attention due to its importance in many engineering fields such as ocean circulation, crystal growth, pollution transportation in air, metal manufacturing process and so on. When heat and mass transfer occur simultaneously in the double diffusive flow, the fluid flow is not only driven by the temperature gradient but also by the concentration gradient as well. In some cases, the Dufour and Soret effects will play a significant role in the double diffusive flow process. The energy flux created by the concentration gradient is called Dufour effect and the temperature gradient can cause the mass flux which is Soret effect. When taking the Soret and Dufour effects into account, the temperature and concentration equations become coupled with each other. However, the coupling diffusivities matrix can be diagonalized. The coupled system can then be transformed to two uncoupled diffusion-advection equations of two independent species. The temperature and concentration can be obtained by the inverse transformation of these two independent species. As a numerical method developed in the past two decades, lattice Boltzmann method (LBM) is powerful in simulating complex heat transfer and fluid mechanics problems. In the current study, a lattice Boltzmann model was developed and implemented for the double-diffusive convection with Soret and Dufour effects. Three distribution functions were used to compute the fluid velocity, specie 1, and specie 2, respectively. Specifically, a rectangular enclosure with horizontal temperature and concentration gradients was investigated. On the other hand, the graphics processing units (GPU) computing becomes popular since the advent of the NVIDIA’s CUDA platform, which includes both hardware components and software programming environment. The developed LBM code was adapted on the CUDA platform to accelerate the computation for parametric studies. The GPU is responsible for the parallel tasks while CPU tackles the sequential steps in the computation. To verify the improvement on computation ability by using GPU, the ratio of the computational time between CPU code and CUDA code is presented by simulating the classical natural convection process in a cavity. The computational speed can be accelerated by more than 20 times when large number of nodes is used. The fluid flow, temperature field and concentration field are presented for different Rayleigh numbers, buoyancy ratios, Prandtl numbers, Lewis numbers, aspect ratios, as well as Soret and Dufour coefficients. In addition, the results of Nusselt and Sherwood numbers are shown for different parametric conditions. As a result, lattice Boltzmann method was demonstrated as a good option to study the complex double-diffusive convection with Soret and Dufour effects in a vertical cavity.
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Saracco, G. P. "Two Driven Diffusive Models." In MODELING OF COMPLEX SYSTEMS: Seventh Granada Lectures. AIP, 2003. http://dx.doi.org/10.1063/1.1571352.
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Ashraf, Shabina, and Jyoti Phirani. "Spontaneous Displacement of Resident Fluid in Heterogeneous Porous Medium." In ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icnmm2018-7737.
Повний текст джерелаАнотація:
Surface tension driven flow in which one fluid displaces another is of importance in microfluidic devices for diagnostics, lab on chip devices and flow in oil reservoirs. Spontaneous impregnation of a preferentially wetting phase displacing an existing non-wetting phase in a homogeneous porous medium is known to follow diffusive dynamics. However, in a heterogeneous porous medium the hydrodynamic interaction between the narrow and the wide pores significantly alters the impregnation behavior. Previous studies have shown that the imbibing fluid interface leads in the narrow pores contrary to the predictions from the diffusive dynamics of homogeneous porous medium. This is due to the higher suction pressure in the narrow pores which draw fluid from the wide pores. The effect of fluid properties and relative flow properties of the pores with respect to other pores on the non-wetting fluid displacement in the heterogeneous porous medium is still unknown. In the current work, we develop a quasi one-dimensional, lubrication approximation model, which predicts the spontaneous imbibition in a heterogeneous porous medium. We explore all the possible relative fluid properties and flow properties of the layers in the heterogeneous porous medium and show that our model is able to predict the flow behavior in all the cases. We also present the results of the spontaneous imbibition experiments, which agree with our model. The experiments show that the two phase interface progresses faster in the narrow pores as predicted by the one-dimensional model. The result is important for predicting and controlling the flow behavior in a heterogeneous porous medium.
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Cocchi, Stefano, Michele Provenzale, Valerio Cinti, Luciano Carrai, Stefano Sigali, and Davide Cappetti. "Experimental Characterization of a Hydrogen Fuelled Combustor With Reduced NOx Emissions for a 10 MW Class Gas Turbine." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-51271.
Повний текст джерелаАнотація:
In the frame of a research project launched in 2006 (partly funded by Regione Veneto, a local institution in the North-East of Italy), ENEL and Nuovo Pignone are developing an innovative “zero emission” gas turbine cycle suitable for power generation. The gas turbine, a GE10-1 model, is manufactured by Nuovo Pignone and will be installed at ENEL’s coal-fired Fusina power plant, near Venice. The turbine, rated for 11 MWe, is equipped with a diffusive flame combustor and is suitable for operation with 100% hydrogen as main fuel over the entire load range. Hydrogen is available at Fusina site as by-product of petrochemical plants. Natural gas will be used as start-up and back-up fuel, and NOx emission abatement will be achieved by means of steam injection. Load operation will be possible with hydrogen only, with methane or hydrogen-methane mixtures (in case of reduced availability of hydrogen) and with or without steam injection. In order to support the combustion system’s design, experimental activities have been carried over a prototypical combustor, installed on a combustion test rig at ENEL’s experimental facility, located in Sesta (Tuscany). The test rig has been upgraded in order to permit full-scale combustor operation. Tests have been planned with the aim of providing a complete screening of combustion system’s sensitivity to minor hardware modification (three different burners and two different liners, designed for diffusive combustion, have been available) and operating conditions (sensitivity to cycle parameters and effect of steam injection). Special instrumentations have been installed for a detailed monitoring of hot parts’ metal temperature, combustion-driven pressure oscillations and pollutant emissions. A water-cooled camera has been installed for direct flame visualization. The experimental campaign is still on-going and only the default combustor configuration has been tested so far. However, collected results indicate safe combustor operation in both hydrogen and methane combustion mode: metal temperatures have never exceeded warning limits and pressure pulsation have been extremely quiet. NOx emission during hydrogen operation in dry combustion mode have been proven to be roughly 3 times higher than in dry methane combustion mode. Steam injection has been proven to be effective in reducing NOx emissions down to contractual values. Additional efforts are in progress to obtain a further reduction of emission level. Finally, experimental results have been processed in order to set up a simple NOx emissions’ model, accounting for NOx production in any possible operating mode.
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li, Li, and Han Yu. "Nonlocal Curvature-Driven Diffusion Model for Image Inpainting." In 2009 Fifth International Conference on Information Assurance and Security. IEEE, 2009. http://dx.doi.org/10.1109/ias.2009.141.
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CAPONE, F. "DIFFUSION-DRIVEN STABILITY FOR BEDDINGTON-DEANGELIS PREDATOR-PREY MODEL." In Proceedings of the 14th Conference on WASCOM 2007. WORLD SCIENTIFIC, 2008. http://dx.doi.org/10.1142/9789812772350_0016.
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Kim, Minkyoung, David Newth, and Peter Christen. "Uncovering Diffusion in Academic Publications Using Model-Driven and Model-Free Approaches." In 2014 IEEE International Conference on Big Data and Cloud Computing (BdCloud). IEEE, 2014. http://dx.doi.org/10.1109/bdcloud.2014.107.
Повний текст джерелаЗвіти організацій з теми "Driven diffusive model"
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Vold, E. L. A model for the effective diffusion of gas or the vapor phase in a fractured media unsaturated zone driven by periodic atmospheric pressure fluctuations. Office of Scientific and Technical Information (OSTI), March 1997. http://dx.doi.org/10.2172/444057.
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Tsimpanogiannis, Ioannis N., and Yanis C. Yortsos. An Effective Continuum Model for the Liquid-to-Gas Phase Change in a Porous Medium Driven by Solute Diffusion: I. Constant Pressure Decline Rates. Office of Scientific and Technical Information (OSTI), August 2001. http://dx.doi.org/10.2172/784395.
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Tsimpanogiannis, Ioannis N., and Yanis C. Yortsos. An Effective Continuum Model for the Liquid-to-Gas Phase Change in a Porous Medium Driven by Solute Diffusion: II. Constant Liquid Withdrawal Rates. Office of Scientific and Technical Information (OSTI), August 2001. http://dx.doi.org/10.2172/784396.
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Epel, Bernard, and Roger Beachy. Mechanisms of intra- and intercellular targeting and movement of tobacco mosaic virus. United States Department of Agriculture, November 2005. http://dx.doi.org/10.32747/2005.7695874.bard.
Повний текст джерелаАнотація:
To cause disease, plant viruses must replicate and spread locally and systemically within the host. Cell-to-cell virus spread is mediated by virus-encoded movement proteins (MPs), which modify the structure and function of plasmodesmata (Pd), trans-wall co-axial membranous tunnels that interconnect the cytoplasm of neighboring cells. Tobacco mosaic virus (TMV) employ a single MP for cell- cell spread and for which CP is not required. The PIs, Beachy (USA) and Epel (Israel) and co-workers, developed new tools and approaches for study of the mechanism of spread of TMV that lead to a partial identification and molecular characterization of the cellular machinery involved in the trafficking process. Original research objectives: Based on our data and those of others, we proposed a working model of plant viral spread. Our model stated that MPᵀᴹⱽ, an integral ER membrane protein with its C-terminus exposed to the cytoplasm (Reichel and Beachy, 1998), alters the Pd SEL, causes the Pd cytoplasmic annulus to dilate (Wolf et al., 1989), allowing ER to glide through Pd and that this gliding is cytoskeleton mediated. The model claimed that in absence of MP, the ER in Pd (the desmotubule) is stationary, i.e. does not move through the Pd. Based on this model we designed a series of experiments to test the following questions: -Does MP potentiate ER movement through the Pd? - In the presence of MP, is there communication between adjacent cells via ER lumen? -Does MP potentiate the movement of cytoskeletal elements cell to cell? -Is MP required for cell-to-cell movement of ER membranes between cells in sink tissue? -Is the binding in situ of MP to RNA specific to vRNA sequences or is it nonspecific as measured in vitro? And if specific: -What sequences of RNA are involved in binding to MP? And finally, what host proteins are associated with MP during intracellular targeting to various subcellular targets and what if any post-translational modifications occur to MP, other than phosphorylation (Kawakami et al., 1999)? Major conclusions, solutions and achievements. A new quantitative tool was developed to measure the "coefficient of conductivity" of Pd to cytoplasmic soluble proteins. Employing this tool, we measured changes in Pd conductivity in epidermal cells of sink and source leaves of wild-type and transgenic Nicotiana benthamiana (N. benthamiana) plants expressing MPᵀᴹⱽ incubated both in dark and light and at 16 and 25 ᵒC (Liarzi and Epel, 2005 (appendix 1). To test our model we measured the effect of the presence of MP on cell-to-cell spread of a cytoplasmic fluorescent probe, of two ER intrinsic membrane protein-probes and two ER lumen protein-probes fused to GFP. The effect of a mutant virus that is incapable of cell-to-cell spread on the spread of these probes was also determined. Our data shows that MP reduces SEL for cytoplasmic molecules, dilates the desmotubule allowing cell-cell diffusion of proteins via the desmotubule lumen and reduces the rate of spread of the ER membrane probes. Replicase was shown to enhance cell-cell spread. The data are not in support of the proposed model and have led us to propose a new model for virus cell-cell spread: this model proposes that MP, an integral ER membrane protein, forms a MP:vRNAER complex and that this ER-membrane complex diffuses in the lipid milieu of the ER into the desmotubule (the ER within the Pd), and spreads cell to cell by simple diffusion in the ER/desmotubule membrane; the driving force for spread is the chemical potential gradient between an infected cell and contingent non-infected neighbors. Our data also suggests that the virus replicase has a function in altering the Pd conductivity. Transgenic plant lines that express the MP gene of the Cg tobamovirus fused to YFP under the control the ecdysone receptor and methoxyfenocide ligand were generated by the Beachy group and the expression pattern and the timing and targeting patterns were determined. A vector expressing this MPs was also developed for use by the Epel lab . The transgenic lines are being used to identify and isolate host genes that are required for cell-to-cell movement of TMV/tobamoviruses. This line is now being grown and to be employed in proteomic studies which will commence November 2005. T-DNA insertion mutagenesis is being developed to identify and isolate host genes required for cell-to-cell movement of TMV.